221 results about "Intra mode" patented technology

The present invention improves residue prediction by using MI even when the base layer MB is encoded in intra mode such as copying intra 4×4 mode of one 4×4 block in the base layer to multiple neighboring 4×4 blocks in the enhancement layer if the base layer resolution is lower than the enhancement layer resolution, using the intra 4×4 mode as intra 8×8 mode if the base layer resolution is lower than the enhancement layer resolution and the base layer resolution is half of the enhancement layer resolution in both dimensions, carrying out direct calculation of the base layer prediction residue used in RP, clipping of prediction residue for reducing memory requirement and tunneling of prediction residue in BLTP mode; and conditional coding of RP flag to save flag bits and reduce implementation complexity

A method and apparatus for Intra prediction mode encoding or decoding based on multi-level most probable modes (MPMs) are disclosed. In one embodiment according to the present invention, the method and apparatus for encoding or decoding Intra prediction mode for 4×4 prediction unit (PU) use 19 Intra mode candidates to have full directional coverage or 35 Intra mode candidates as used by 8×8, 16×16 and 32×32 PUs. In another embodiment of the present invention, three MPMs are used to code the Intra modes. Various methods to derive the three MPMs based on the Intra modes of neighboring blocks are disclosed. In yet another embodiment of the present invention, the coding method for the remaining modes comprises fixed length coding. In addition, variable length coding for the remaining modes are also disclosed.

Disclosed herein is an adaptive motion estimation and mode decision apparatus and method for an H.264 video codec. The apparatus includes a background image detection unit, an inter mode inspection unit, an intra mode inspection unit and a mode inspection skip unit. The background image detection unit inspects whether a fixed background or slowly and regularly moving block exists, and skips the step of dividing a first corresponding macroblock into smaller sized blocks and performing block mode inspection. The inter mode inspection unit inspects whether an irregularly or fast moving macroblock exists, and determines whether to divide a corresponding macroblock into smaller sized blocks and to perform block mode inspection on the smaller sized blocks. The intra mode inspection unit performs AZCB inspection on the macroblocks, and determines whether to divide a corresponding macroblock into smaller sized blocks block and to perform mode inspection on the smaller sized blocks. The mode inspection skip unit skips the block mode inspection for the smaller sized blocks.

Provided is a method for decoding video, which performs prediction in an intra mode. The method for decoding video according to the invention comprises steps of: creating a current table index using a code number and MPM index information; and deriving a current prediction mode by adopting an index mapping table in the current table index. According to the present invention, video encoding / decoding efficiency can be improved.

The temporal and / or spatial characteristics of a macroblock are analyzed in order to reduce the number of modes for which motion estimation and rate distortion efficiency calculations are to be performed. In one embodiment, macroblock mean and variance characteristics are analyzed to merge sub-blocks together within the macroblock. These merged sub-blocks may be used to identify both inter and intra modes for the macroblock.

A method and device for coding a digital image using intra-mode block prediction, wherein a list of prediction modes for each combination of prediction modes of the neighboring blocks is obtained. The modes assigned to each combination of prediction modes may be divided into two groups. The first group includes n (where n is smaller than the overall number of available modes) most probable prediction modes and the second group includes the remaining modes. The modes in the first group are ordered according to their probability. This order may be specified as a list of modes ordered from most probable to the least probable mode. The modes belonging to the second group may be ordered in some predetermined manner, which may be specified depending on the information already available to the decoder.

The invention relates to a method and device for encoding digital video data corresponding to an original sequence of images and available in the form of a video stream consisting of successive pictures which are either INTRA pictures or INTER pictures. The INTRA pictures are called I-pictures and encoded by means of a so-called INTRA mode without any reference to any past or future picture. The INTER pictures are either monodirectionally predicted pictures, called P-pictures and encoded with reference to a past or future reference picture which is an INTRA or INTER picture, or bidirectionally predicted pictures, called B-pictures and encoded with reference to one or more reference picture(s). The INTRA pictures themselves comprise either I-pictures placed at the beginning of a new group of pictures corresponding to a scene change, where no temporal redundancy is available, and called scene change I-pictures, or I-pictures placed in other locations, where some temporal redundancy is available, and called refresh pictures. According to the invention, the method is characterized in that, before being quantized and encoded in INTRA mode, said INTRA refresh pictures are replaced by an INTER picture having quality and artefacts substantially similar to those of the last encoded INTER picture(s).

An image encoding method according to the present invention calculates first difference information of an encoding target block and second difference information of an adjacent block, calculates a difference between the first difference information and the second difference information, and uses an intra mode only for blocks where a residual image noise occurs by selecting the intra mode when the difference is larger than a predetermined threshold, and selecting an inter mode when the difference is smaller than the predetermined threshold.

The invention discloses a fast and efficient video coding intra mode determining method. The fast and efficient video coding intra mode determining method includes the steps of prediction manner configuration and prediction mode selection. According to the prediction mode selection, the correlations between brightness intra prediction modes of a current CU layer and brightness intra prediction modes of CU layers above the current CU layer, the correlation between CBF and TU segmentation depth, and the correlations between chroma intra prediction modes of adjacent CU layers are utilized, and redundant intra mode prediction can be skipped, and therefore, coding computation complexity can be decreased. According to the correlation between a cost function and RDcost and the correlations between chroma intra prediction modes and brightness intra prediction modes, a minimum-cost prediction mode and an optimal brightness prediction mode in RMD are added in a brightness and chroma intra prediction process, and therefore, video coding efficiency and video quality can be ensured. Compared with high efficiency video coding (HEVC) standards in the prior art, the fast and efficient video coding intra mode determining method of the invention can greatly decrease coding computation complexity under the premise that bit rate and video quality are almost unchanged.

A method and apparatus for video coding of chroma coded in derived-mode Intra prediction are disclosed. If derived-mode (DM) Intra prediction is selected for a current chroma block, a corresponding luma block area is determined by locating a first upper-left pixel address of the corresponding luma block area corresponding to that of the current chroma block; one or more candidate luma coding modes are determined from a sub-block set consisting of one or more sub-blocks of the corresponding luma block area, where if the sub-block set consists of only one sub-block, the sub-block set excludes a corner sub-block located at a top-left corner of the corresponding luma block area; a current chroma Intra mode for the current chroma block is derived based on information comprising the candidate luma coding modes; and Intra-prediction encoding or decoding is applied to the current chroma block using the current chroma Intra mode derived.

In video encoding and decoding predictions may be generated by intra-frame prediction. Intra-frame prediction uses reconstructed pixels in a reconstructed frame. Intra-frame prediction is performed by extending the reconstructed pixels into a predicted block using intra-frame prediction modes, each intra-frame prediction mode indicating a direction of the extension. In order to reduce the number of possible intra-frame prediction modes, a subset is selected from a predetermined set of possible intra-frame prediction modes. A subset of intra-frame prediction modes can be created by forming preselection sets of intra-frame prediction modes on the basis of similarity of their associated predicted blocks and selecting a representative intra-frame prediction mode from each preselection set.

Provided is a method for decoding video, which performs prediction in an intra mode. The method for decoding video according to the invention comprises steps of: creating a current table index using a code number and MPM index information; and deriving a current prediction mode by adopting an index mapping table in the current table index. According to the present invention, video encoding / decoding efficiency can be improved.

A prediction mode for encoding data is selected using a reduced number of rate-distortion cost computations. This reduction in rate-distortion cost computations is caused by filtering the number of potential intra prediction modes based on two criteria. First, the number of potential prediction modes is reduced based on at least one characteristic of a quantization procedure performed during the encoding procedure. Second, the number of potential prediction modes is reduced based on an error value calculated for each of the potential prediction modes.

A method for scalably encoding and decoding a video signal is provided. If a frame temporally coincident with a current frame in an enhanced layer including a target macroblock is not present (i.e., if there is a missing base layer frame) in a base layer when the target macroblock is predicted during encoding of the enhanced layer, the target macroblock is encoded in an intra mode using a past and / or future frame of the base layer prior to and subsequent to the current frame. Thus, inter-layer prediction can be applied even to a missing picture when a video signal is scalably encoded, thereby increasing coding efficiency.

A method for cross-color Intra prediction using the LM Intra mode using multi-row or multi-column neighboring reconstructed pixels for LM parameter derivation or using only top pixels or left pixels of neighboring pixels is disclosed. Multiple LM Intra modes can be used. For example, three LM Intra modes can be used and the LM parameters for the three LM Intra modes can be determined based on only the top pixels, only the left pixels and both the top pixels and left pixels of neighboring reconstructed pixels respectively. To remove the need for additional buffer requirement for deriving the LM parameters based on using multi-row or multi-column neighboring reconstructed pixels, the current method re-uses existing buffers, where the buffers are used for deblocking. A syntax element can be used to indicate one of the multi-LM modes selected.

A method and apparatus are provided for effectively predicting a video frame that use all of the advantages of an intra mode and an intra BL mode in multi-layer structure based-video coding. The method includes reconstructing the intra block of a lower layer using the previously reconstructed first neighboring blocks of the intra block; subtracting the first neighboring blocks from previously stored the second neighboring blocks of an upper layer corresponding to the first neighboring blocks; creating a differential predicted block based on a predetermined intra prediction mode by performing intra prediction using virtual differential neighboring blocks that are created as a result of the subtraction; adding the differential predicted block and the reconstructed intra block; and subtracting a predicted block, which is created as a result of the addition, from a block of the upper layer corresponding to the intra block.

Disclosed is a method for decoding an image block. The method comprises a step of decoding an image block of a first layer based on a corresponding block of a second layer encoded with an intra mode, wherein a first area is formed with pixels, which are adjacent to a corner pixel positioned in the corresponding block in a diagonal direction and extend in vertical and horizontal directions away from the corresponding block, and data are padded in the first area based on the corner pixel and the pixels positioned in the first area and at least one of first and second blocks, which are simultaneously adjacent to the corresponding block and encoded with the intra mode. Accordingly, a reference block required when a macro block is encoded in an intra base mode or when a macro block encoded in the intra base mode is decoded has more precise values, thereby enabling improvement of a coding efficiency.

A method and device for coding a digital image using intra-mode block prediction, wherein a list of prediction modes for each combination of prediction modes of the neighboring blocks is obtained. The modes assigned to each combination of prediction modes may be divided into two groups. The first group includes n (where n is smaller than the overall number of available modes) most probable prediction modes and the second group includes the remaining modes. The modes in the first group are ordered according to their probability. This order may be specified as a list of modes ordered from most probable to the least probable mode. The modes belonging to the second group may be ordered in some predetermined manner, which may be specified depending on the information already available to the decoder.

The invention discloses an intra mode prediction method, an intra mode prediction device and a coder. The method comprises the following steps of: when the optimal mode of an adjacent left block is a horizontal mode, taking the horizontal mode as the most possible mode of a block to be coded; when the optimal mode of an adjacent upper block is a vertical mode, taking the vertical mode as the most possible mode of the block to be coded; when the optimal modes of the adjacent left block and the adjacent upper block are the same, taking the same mode as the most possible mode of the block to be coded; when the serial numbers of the optimal modes of the adjacent left block and the adjacent upper block belong to a set {8, 6}, taking the horizontal mode as the most possible mode of the block to be coded, and when the mode serial numbers of the optimal modes of the adjacent left block and the adjacent upper block belong to a set {3, 4} or {7, 5}, taking the vertical mode as the most possible mode of the block to be coded; and selecting the optimal mode in the optimal modes of the adjacent left block and the adjacent upper block, which has a smaller mode serial number, as the most possible mode of the block to be coded. The embodiment of the invention can improve the accuracy of intra mode prediction.

A video signal coding method is provided which finds proper decision curves according to characteristics of input frames and encodes the optimal macroblock by using the decision curves instead of a fixed motion / no-motion compensation curve and intra / inter coding curve. The optimal mode is selected for each macroblock of input frame and it is determined through a step of judging whether the input frame is intra mode using a given function, a step of judging whether the input frame is inter mode when it is not intra mode using a given function, a step of controlling quantizer using a predetermined critical value when it is not inter mode, and step of performing skip when the quantizer controlling step is not carried out.

A computer readable storage medium has executable instructions to select a plurality of blocks in a video sequence to be coded as intra-coded blocks. Aggregate intra prediction costs are computed for each intra-coded block relative to a corresponding previous intra-coded block. An intra prediction mode is selected for each intra-coded block based on the aggregate intra prediction costs.

An image intra prediction method and image intra prediction apparatus and a decoding apparatus and a decoding method using the image intra prediction method are provided. The image intra prediction method includes: backing up boundary pixel values adjacent to a block that is to be decoded; correcting the boundary pixel values adjacent to the block that is to be decoded based on correlations between the boundary pixels and pixels adjacent to the boundary pixels; predicting a block that is to be decoded according to an intra mode, from among a plurality of intra modes, based on the corrected boundary pixel values; and restoring the boundary pixel values from the backed-up values.

The vector detecting unit detects a motion vector even for a block that is encoded in the intra mode, and the detected motion vector is stored in the reference vector storing unit. Even for a block that has been encoded in the intra mode, the initial vector calculating unit calculates an initial point with the use of a reference vector, the initial point serving as an initial point used in a motion vector detection process during hierarchical block matching. Thus, it is possible to calculate an initial point with a high precision level with the use of motion information from the vicinity of a target block for which a motion vector is to be detected.

A method compensates for drift in macroblocks of a partially decoded input bitstream. The macroblocks include intra-mode and inter-mode macroblocks, and each macroblock includes DCT coefficients, and at least one motion vector. An estimate of drift is measured in the partially decoded input bitstream. The estimated drift is translated into an intra refresh rate. The modes of inter-mode macroblock are mapped to intra-mode macroblock according to the refresh rate. The DCT coefficients and the motion vector for each changed macroblock are modified in accordance with the mapping for each changed macroblock.

In video encoding and decoding predictions may be generated by intra-frame prediction. Intra-frame prediction uses reconstructed pixels in a reconstructed frame. Intra-frame prediction is performed by extending the reconstructed pixels into a predicted block using intra-frame prediction modes, each intra-frame prediction mode indicating a direction of the extension. In order to reduce the number of possible intra- frame prediction modes, a subset is selected from a predetermined set of possible intra- frame prediction modes. A subset of intra-frame prediction modes can be created by forming preselection sets of intra-frame prediction modes on the basis of similarity of their associated predicted blocks and selecting a representative intra-frame prediction mode from each preselection set.